Insulated glass (IG) assemblies are used in most window and door applications. IG assemblies are constructed of two or more sheets (panes) of glass, and a spacer including a stabilizer and sealant strip placed between the sheets and extending around the entire perimeter of the panes. The separated glass panes create an envelop of dead air which when used in a window or door, greatly reduces the passage of heat through the pane.
It has long been desirable to incorporate lighting systems into IG assemblies. Internally illuminating IG assemblies could replace exterior light systems in front of windows and doors with more aesthetically pleasing and unobtrusive internal lighting systems. Internally illuminated IG assemblies provide illumination on both sides of a window or doorway, which adds an important safety feature to any window or doorway. Since the light is enclosed within the window's IG assembly, the light cannot be tampered with without detection. Internally illuminated IG assemblies provide an improved aesthetic appearance by accenting various sculptured and stained glass panes.
Attempts, however, to incorporate internal lighting systems into IG assemblies have been unsuccessful and impractical. Heretofore, attempts at internally illuminating insulated glass units involved inserting conventional incandescent lights into the sealed air space between glass panes. Conventional incandescent lights are ill suited for use in IG assemblies for a variety of reasons. One obvious problem is the relatively short life span of even the best incandescent lamp. Once a lamp filament burns out, the entire glass unit must be replaced, which makes such IG assemblies cost prohibitive. A more subtle, but equally significant problem is the thermal energy emitted from the conventional incandescent lights. Incandescent lights emit visible light as a result of heating a filament with an electric current. The electrical current passing through the filament generates significant thermal energy. This thermal energy can cause significant contraction and expansion of the spacer bar, which can result in air leakage and a less efficient insulated glass pane. The thermal energy can also break down the sealant and desiccant materials of the spacers. Reducing the current flow through the filament only slightly reduces the thermal energy problem, but also proportionately reduces the illumination of the light. Fluorescent and neon lights produce relatively low thermal energy, but are impractical for use in insulated glass due to the cost and physical nature of incorporating fluorescent or neon tubes as spacer bars of insulated glass panes. Consequently, a low thermal energy emitting light source, and an effective mechanism for heretically sealing the light source within the air space is needed to create a practical internally illuminated glass pane.